Add Separator: ipynb compatibility

Revert the behaviour change of ipynb duplicate items

src/magicgui/backends/_ipynb/widgets.py

@@ -221,7 +221,6 @@ def _mgui_get_choices(self) -> tuple[tuple[str, Any]]:
     def _mgui_set_choices(self, choices: Iterable[tuple[str, Any]]) -> None:
         """Set available choices."""
         options = [item for item in choices if item[1] is not Separator]
-        options = list(dict(options).items())  # remove duplicate names, last data used
         self._ipywidget.options = options
 
     def _mgui_del_choice(self, choice_name: str) -> None:

tests/test_widgets.py

@@ -1098,14 +1098,18 @@ def get_all_itemdata(combo_box):
         assert get_all_itemdata(widget_with_separator.a.native) == a
         assert get_all_itemdata(widget_with_separator.b.native) == b2
 
+        # Choices only returns unique, non-separator items
+        assert widget_with_separator.a.choices == (1, 2, 4, 6, 7, 9, 11, 12, 14)
+        assert widget_with_separator.b.choices == (1, 2, 4, 6, 7, 9)
+
     if backend == "ipynb":
         # Separator singletons themselves are used as separator item data
         assert widget_with_separator.a.options['choices'] == a
-        assert widget_with_separator.b.options['choices'] == b  # non-separators are not unique
+        assert widget_with_separator.b.options['choices'] == b  # items are not unique
 
-    # Choices only returns unique, non-separator items
-    assert widget_with_separator.a.choices == (1, 2, 4, 6, 7, 9, 11, 12, 14)
-    assert widget_with_separator.b.choices == (1, 2, 4, 6, 7, 9)
+        # Choices only returns duplicated, non-separator items
+        assert widget_with_separator.a.choices == (1, 2, 4, 6, 7, 9, 11, 12, 14)
+        assert widget_with_separator.b.choices == (1, 2, 4, 6, 7, 9, 6, 7, 9)
 
 
 def test_float_slider_readout():